As the size of communication devices, such as cellular telephones, is reduced, typically the size of the antenna is required to be reduced as well. However, basic properties of the antenna may limit the freedom that a designer has to reduce the size of the antenna without adversely affecting the overall antenna performance. A paper titled “Introduction to Ultra-Wideband Antennas,” by Schantz, presented at the IEEE Conference on Ultra Wideband Systems and Technologies, November, 2003, describes some of the limitations that the author believes may hold for antennas. The paper is incorporated herein by reference.
The effect of a chassis to which the antenna is coupled is evaluated in a paper titled “Resonator-Based Analysis of the Combination of Mobile Handset Antenna and Chassis,” by Vainikainen et al., published in IEEE Transactions on Antennas and Propagation, Vol. 50, No. 10, October, 2002. The paper is incorporated herein by reference.
Finnish Patent Fl 114260 B, to Vainikainen et al., which is incorporated herein by reference, describes a coupling device for sending or receiving RF signals. The patent describes an antenna using radiation from a ground plane.
In a paper titled “Thin dual-resonant stacked shorted patch antenna for mobile communications,” by Ollikainen et al., published in Electronic Letters Volume 35, number 6, in March, 1999, the authors describe an antenna constructed from two stacked patches. The paper is incorporated herein by reference. One of the patches is a driven element, while the other acts as a parasitic element. The driven patch is formed on one side of a 1.6 mm substrate, on the other side of which is formed a ground plane. The parasitic patch is stacked above the driven patch, making the total height of the antenna 4 mm.
U.S. Patent Application 2003/0201942 A1, to Poilasne et al., which is incorporated herein by reference, describes a multi-band antenna. The antenna comprises one or more first plates and one or more second plates. The plates are mounted over a ground plate.
In a paper titled “A Low-Profile Antenna Solution for Mobile Phones with GSM, UMTS and WLAN Operation,” by Rennings et al., presented at the European Microwave Conference, Paris, France in October, 2005, the authors describe an antenna formed by printing dual-layers on a substrate. The paper is incorporated herein by reference.
In a paper titled “Low-Profile Planar Monopole Antenna for GSM/DCS/PCS Triple-Band Mobile Phone,” by Lee et al., and published in the IEEE Antennas and Propagation Society International Symposium 2002, Volume 3, pages 26-29, the authors describe an antenna printed on a substrate. The paper is incorporated herein by reference. The antenna has a single feed point with a microstrip feed line.
PCT Patent Application WO 2004/027922, to Kadambi et al., which is incorporated herein by reference, describes an antenna which may be printed on a substrate. The antenna is connected to one region of a ground plane on the substrate.